1. Field of the Invention
The present invention is broadly concerned with antibodies specific to antigens of Bartonella henselae and use of these antigens in immunoassays. More particularly, the present invention relates to antibodies specific to the GroES protein, the RpIL protein, an expressed protein of unknown function (the “BepA” protein), the GroEL protein, the SodB protein, the UbiG protein, and the ABC transporter protein of Bartonella henselae, and use of these antigenic proteins in immunoassays in order to determine whether a patient is or was infected with Bartonella henselae. 
2. Description of the Related Art
Epidemiological, serological, and molecular studies have implicated Bartonella henselae as the primary causative agent of Cat Scratch Disease (CSD), a frequent self-limiting zoonotic condition which is transferred from cat scratches or bites to people (Bergmans, A. M., J. W. Groothedde, J. F. Schellekens, J. D. van Embden, J. M. Ossewaarde, and L. M. Schouls. 1995. Etiology of cat scratch disease: comparison of polymerase chain reaction detection of Bartonella (formerly Rochalimaea) and Afipia felis DNA with serology and skin tests. J. Infect. Dis. 171:916-23). Development of CSD is common with a reported incidence rate of 0.77 to 0.86 cases per 100,000 people.
In the United States, approximately 22,000 people develop CSD annually (Koehler, J. E., C. A. Glaser, and J. W. Tappero. 1994. Rochalimaea henselae infection. A new zoonosis with the domestic cat as reservoir. JAMA 271:531-5; Peter, J. B., M. Boyle, M. Patnaik, T. L. Hadfield, N. E. Barka, W. A. Schwartzman, and R. S. Penny. 1994. Persistent generalized lymphadenopathy and non-Hodgkin's lymphoma in AIDS: association with Rochalimaea henselae infection. Clin. Diagn. Lab. Immunol. 1:115-6). Approximately 11% of CSD cases are atypical and symptoms can include granulomatous conjunctivitis, oculoglandular syndrome, tonsillitis, visceral granulomatous disease, encephalitis, and cerebral arteritis (Schwartzman, W. A. 1992. Infections due to Rochalimaea: the expanding clinical spectrum. Clin. Infect. Dis. 15:893-900).
Cats serve as a major reservoir of Bartonella henselae. Pathogen analyses of domesticated cats in the United States have estimated that approximately 28% are chronically infected with Bartonella henselae with no obvious clinical symptoms (Kordick, D. L., K. H. Wilson, D. J. Sexton, T. L. Hadfield, H. A. Berkhoff, and E. B. Breitschwerdt. 1995. Prolonged Bartonella bacteremia in cats associated with cat-scratch disease patients. J. Clin. Microbiol. 33:3245-51).
Infection with Bartonella henselae in significant cases can result in bacillary angiomatitis or endocarditis. Children and immunocompromised individuals are especially vulnerable to this bacterium. In immunocompromised patients, including those who have been infected with HIV-1 and have developed AIDS, infection with Bartonella henselae can result in bacillary angiomatosis or peliosis hepatis and may also include visceral involvement (Fournier, P. E., and D. Raoult. 1998. Cat scratch disease and an overview of other Bartonella henselae related infections, p. 32-62. In A. Schmidt (ed.), Bartonella and Afipia species emphasizing Bartonella henselae. Karger, Basel, Switzerland.). The U.S. Public Health Service and the Infectious Diseases Society of America have recognized the risk of contracting Bartonellosis, especially in immunocompromised HIV-1 infected individuals, and have published suggested guidelines for cat ownership as feline-to-human transmission of Bartonella henselae is the most commonly recognized route (Kaplan, J. E., H. Masur, and K. K. Holmes. 2002. Guidelines for preventing opportunistic infections among HIV-infected persons—2002. Recommendations of the U.S. Public Health Service and the Infectious Diseases Society of America. MMWR Recomm. Rep. 51:1-52.).
Bartonella spp. also have been found in 39% of deer ticks (species: Ixodes scapularis) (Adelson, M. E., R. S. Rao, R. C. Tilton, K. Cabets, E. Eskow, L. Fein, J. C. Occi, and E. Mordechai. 2004. Prevalence of Borrelia burgdorferi, Bartonella spp., Babesia microti, and Anaplasma phagocytophila in Ixodes scapularis ticks collected in Northern New Jersey. J. Clin. Microbiol. 42:2799-801). This information, in conjunction with a clinical case study in which patients were co-infected with Borrelia burgdorferi, the causative agent of Lyme Disease, and Bartonella henselae, suggests that tick bites may serve as an additional method of Bartonella henselae transmission (Eskow, E., R. V. Rao, and E. Mordechai. 2001. Concurrent infection of the central nervous system by Borrelia burgdorferi and Bartonella henselae: evidence for a novel tick-borne disease complex. Arch. Neurol. 58:1357-63).
Current clinical diagnostics rely on culturing, immunofluorescence assay (“IFA”), and polymerase chain reaction (“PCR”) technologies. The culturing of Bartonella from blood samples is technically challenging and is a low-yield procedure. Recommended growth conditions include lengthy incubation periods of at least twenty-one days on Columbia blood agar plates (Raoult, D., and R. Tilton. 1999. Dictionary of Infectious Diseases. Elsevier Publishing, New York; Spach, D. H., and J. E. Koehler. 1998. Bartonella-associated infections. Infect. Dis. Clin. North. Am. 12:137-55). Culturing of Bartonella is therefore not considered an effective and reproducible diagnostic procedure to detect Bartonella spp. infections.
Bartonella henselae IFAs have high sensitivity and specificity. However, cross-reactivity with other human pathogens, including Coxiella burnetii, Chlamydia spp., Rickettsia rickettsii, Ehrlichia chaffeensis, Treponema pallidum, Francisella tularensis, and Mycoplasma pneumoniae has been reported (Cooper, M. D., M. R. Hollingdale, J. W. Vinson, and J. Costa. 1976. A passive hemagglutination test for diagnosis of trench fever due to Rochalimaea quintana. J. Infect. Dis. 134:605-9.; Drancourt, M., J. L. Mainardi, P. Brouqui, F. Vandenesch, A. Carta, F. Lehnert, J. Etienne, F. Goldstein, J. Acar, and D. Raoult. 1995. Bartonella (Rochalimaea) quintana endocarditis in three homeless men. N. Engl. J. Med. 332:41923.; McGill, S. L., R. L. Regnery, and K. L. Karem. 1998. Characterization of human immunoglobulin (Ig) isotype and IgG subclass response to Bartonella henselae infection. Infect. Immun. 66:5915-20.). In addition, IFAs rely heavily on technicians for the determination of test results which introduces subjectivity into the interpretation of these test results, are time-consuming to score, and require expensive fluorescent microscopes.
Bartonella PCR amplifies the 16S rRNA gene which permits the simultaneous detection of DNA from Bartonella henselae, Bartonella quintana, Bartonella bacilliformis, Bartonella elizabethae, and Bartonella clarridgeiae (Bergmans, A. M., J. W. Groothedde, 3. F. Schellekens, J. D. van Embden, J. M. Ossewaarde, and L. M. Schouls. 1995. Etiology of cat scratch disease: comparison of polymerase chain reaction detection of Bartonella (formerly Rochalimaea) and Afipia felis DNA with serology and skin tests. J. Infect. Dis. 171:916-23). While allowing for species-specific identification, PCR requires the presence of Bartonella organisms or DNA in the tested sample.
The antibody response to Bartonella henselae has been studied in several different types of mammals; however, in order to develop sensitive and accurate serological assays, for example, the human antibody response to Bartonella henselae needs to be elucidated in detail. Identification of antigenic proteins, particularly, is of paramount importance to the creation of improved clinical diagnostics.